1. Field
Example embodiments relate to a green light-emitting device including a quaternary quantum well on a vicinal c-plane.
2. Description of the Related Art
A light-emitting device including a light-emitting layer formed of a Group-III nitride material such as GaN, AlN, InN, or the like emits bright light from an infrared light wavelength spectrum to green light wavelength spectrum. However, in such a light-emitting device, an internal electric field is typically formed, which is caused by a spontaneous polarization field depending on a direction of a crystallographic axis and a polarization field induced by strain generated due to a lattice constant difference with a substrate. The spontaneous polarization field is generally strongest when the direction of the crystallographic axis is <0001> (that is, a polar direction), and the strength of the spontaneous polarization field decreases in a non-polar direction (that is, an m-plane). As electrons and holes are spatially separated due to the internal electric field, a light-emission coupling rate decreases, thus degrading the performance of the light-emitting device. In particular, an InGaN-based quantum well light-emitting device has low light-emission efficiency with respect to a green wavelength.
To reduce the internal electric field, a light-emitting layer may be grown in a non-polar direction or semi-polar direction of a growth substrate. In addition, a miscut substrate may be used to reduce the internal electric field.